After years of fielding queries from well-rested travelers who were threatening to pack up not only the shampoo but also the bed, a number of hotels got wise and went into the bedding-retail business. Today you can buy a mattress just like the one you sank into at the Marriott. Or Westin. Or Hilton. And so on. Best part: If you need shopping advice, you can dial the hotel's nice-sounding "mattress concierge."